Switch mode power supply working principle:

Principle of Switch mode power supply control regulator for voltage stabilization:

Switch knob turn on and off repeatedly to a certain time interval, when the switch is turned on, the input power supply through switch knob and filter circuit to supply loading, during the entire switch turn on duration, the power supply provided energy to loading;
When switch disconnected, input power supply interrupted to provide energy. Be seen, the input power supply to provide energy for load is intermittent, in order to load can be obtain a continuous energy power supply, switching mode power supply must have a energy storage device, when the switch turns on, there is a part of energy stored in the switch, when disconnect, the stored energy will release to load. Inductance used to store energy, when the switch is off, stored energy in the inductance through the diode release to the load, make sure that the load to obtain a continuous and stable energy, because the diode enable load to get continuous current, so called continuous current diodes. This is the way switch mode power supply working

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Switch mode power supply formula:

EAB in the average voltage between AB can be expressed as:
EAB=TON/T*E
TON wherein as each switch turn on time, T is the switching-off working cycle (ie, switch on-time TON and off-time TOFF together value).
By the equation, change the ratio of switch on-time and working cycle, the average voltage between AB also changed, therefore, as the load and input supply voltage changes automatically adjust the ratio of TON and T will cause the output voltage V0 remain unchanged. Changing the on-time working cycle TON proportions and that meanschanging the pulse duty cycle, this method is called as “time ratio control” (Time Ratio Control, abbreviated as TRC).

switch mode power supply